This competing renewal application is submitted to support continuation of the Program Project TMD Longitudinal Studies: Clinical/Chronic Pain Syndromes. The overall goal is to conduct multidisciplinary research on the onset, natural history, care and prevention of pain and dysfunction associated with temporomandibular disorders (TMD). The research concern temporomandibular disorders as clinical entities and dysfunctional chronic pain associated with TMD. TMD refers to a set of disorders characterized by pain and tenderness in the muscles of mastication and/or the temporomandibular joint (TMJ), limitations of jaw opening and clicking, popping or grating TMJ sounds. Dysfunctional chronic pain is defined as chronic-recurrent pain of moderate-severe intensity that limits activities. Dysfunctional chronic pain is associated wit emotional disturbance, elevated rates of illness behavior and impaired performance of major social roles. The proposed Program Project will continue to focus on TMD as a clinical entity, the adaptation of the chronic pain patient to TMD pain and the response of the health care delivery system to the TMD pain patient. An integral part of the research strategy has been and will continue to be comparison of TMD with other common chronic pain conditions, principally back pain and headache. We propose to carry out four projects: The first Project will study the nature, determinants, development and prevention of chronic pain behaviors associated wit TMD, back pain and headache. This research will focus on care-related chronic pain behaviors (health care visits and use of pain medications) that are behavioral manifestations of patient entry into a chronic sick role. The next project will investigate how to improve dentists' knowledge and practice concerning biomedical, behavioral and psychosocial aspects of the management of TMD. Experimental studies of educational interventions will be carried out among practicing dentists and among dental students. The last project will assess, through a randomized controlled trial, the relative effectiveness of conventional flat plane occlusal splint therapy compared to both a low cost alternative to splint therapy a flat plane bit appliance fabricated by the patient-- and to usual TMD care without splint therapy. A Core Project will consist of a Scientific Core providing scientific direction, project coordination, design and analysis resources, integrated data management, and shared scientific expertise.